TBM Drives at the Gotthard Base Tunnel - Amberg GroupTBM Drives at the Gotthard Base Tunnel 29.8.2017 AFER Certification – Meeting with Amberg Engineering AG Project Main Information

TBM Drives at the Gotthard Base Tunnel

29.8.2017

AFER Certification – Meeting with Amberg Engineering AG

TBM Drives at the Gotthard Base Tunnel Challenges in the Faido section

Thomas Jesel, MSc, Amberg Engineering AG


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29.8.2017


Project Main Information

Client Alp Transit AG (ATG)

Location Switzerland

Design Level All design stages up to detailed design

Design Joint Venture JV with Pöyry Infra AG and Lombardi SA under lead of Amberg Engineering AG

Project Phases & Design Schedule Design 1990-2016 Construction 1993-2016 Commissioning 2017

Design Costs 485 Mio. CHF (part of AE: 165 Mio. CHF)

Total Project Costs 12.2 billion CHF


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Design Responsibilities

Preliminary Design Amberg within JV, responsible for the whole tunnel itself

Basic Design Amberg within JV, responsible for the whole tunnel itself

Detailed Design Amberg within JV, responsible for the Faido section

Tender Design Amberg within JV, responsible for the Faido section

Assistance on Site Amberg within JV, responsible for Bodio, Faido and partially Sedrun

Site Supervision Amberg within JV, mainly Faido but also Bodio and Sedrun


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Gotthard Base Tunnel, www.alptransit.ch

http://www.alptransit.ch/


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Excavation method


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TBM

4 Herrenknecht TBM

Open gripper shield

Length

TBM: 26 m

Back-up: 450 m

Cutter head

Diameter: 9.43 m

Shifted, max: 9.53 m

Weight: 240 t

Discs:

Number: 66

Diameter: 17’’


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Experience Faido

Cutter head wear

Water inflow

Rock burst

Squeezing rock

Blocked TBM

Excavation rates


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Cutter head wear I

Abrasivity with Cherchar index

Tender design: CAI 2.8

Medelser Granite CAI 4.4

Lucomagno Gneiss CAI 3.4

Medelser Granit

Lucomagno Gneis


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Cutter head wear II

Instable face

Not all discs at face

Reduced face pressure

Reduced cutting speed

Blocks at the face

Cutter head as crusher

Rolling blocks hits the disks


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Cutter head wear III

CAI much higher than prognosis

Damaged Disks due to blocks

Often longer maintenance shifts

Reduced pressure due to instable

face

Determinating for advance rate


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Water inflow I

Water pressure up to 200 bar

Probe drillings require preventer

(in sensitive areas)

Needs specification in tender docs

1:1 tests on site recommended

before start

Works well for both percussion

and core drillings


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Water inflow II

Water inflow initial max 100 l/s

Ascending tunnel

600 mm drainage pipe

No problem

But 48°C!

Cooling system limited

Reduced working hours

Frequent pauses required

Reduced advance rate


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Rock burst I


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Rock burst II

Difficult to predict

Without warning – suddenly!

Rock support cannot prevent

rock burst

But must protect staff

TBM helps!

Absorb kinetic energy

Not easy to classify,

subjective

Code of classification

Potential measures


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Squeezing rock I

Started with Steel arches and

rock bolts and shotcrete

Soon deformations (30 cm)

Shotcrete destroyed

Steel arches plastified


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Squeezing rock II

Second TBM even worse

Back up was squeezed in

Heave in the invert

Reconstruction of the invert

still under the TBM


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Squeezing rock III

TBM got through – at the end

Intensive back calculations

New loads, new design

Tunnel redone on 400 m


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Squeezing rock IV

D&B in this area had less problems

Rock support can be installed direct

at the front, with TBM not possible

Distance between face and installed

rock support is important

Shield must be as short as possible

Styrofoam elements worked well to

protect young shotcrete

Inclined cross passages allowed to

redo the tunnels without interrupting

the TBM


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Blocked TBM I

First machine passed

Some over brake

Second machine got stocked

Several attempts with backing

and restart were not successful

1’100 m spiles installed

Voids filled up with 48 m3

concrete and 47 m3 grout


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Blocked TBM II

Still not successful

A lot of material was taken

out without any progress

Massive cavern above tunnel

Extensive probe drilling


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Blocked TBM III

Stabilize loos material

Grouting campaign from a niche,

east tunnel

Counter heading to secure the time

schedule


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Blocked TBM IV

Action plan was very helpful,

reduced reaction time significantly

Expert panel was important

Close collaboration and clear

communication was crucial

Decision need to be taken fast,

immediately at the face

Willingness to solve the problem

compulsory


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Ost West

Penetration mm/U 8.28 8.46

Netto advance rate m/h 2.51 2.64Advance rates I

Design: 2.33 m/h


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Advance rates II

Joint and foliation angle

important influence

Penetration around 10 mm

while perpendicular

Drops down to 70% while flat


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Advance rates III


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Lessons learned I

Optimize TBM for most probable

geology – set right focus

Make sure, that TBM can handle

worst case

Open gripper TBM was right

decision - flexibility was needed

Shotcrete in L1 was necessary and

feasible, main shotcrete in L2

Rock bolts in L2 were not used.

Bolts are needed as close to the

face as possible


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Lessons learned II

A continuous probe drilling from the

TBM was very useful (low cost, no

time)

In such difficult geology it is

inevitable to have competent staff on

site (contractor, designer bust also

client)

Decisions need to be taken fast, to

keep TBM running

Logistic is important. Keep other

activities as low as possible

TBM produces a lot of data. Data

evaluation needs a clear concept to

get significant results


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Main challenge: Communication!


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Thank you for your attention! [email protected]

Boot 31

Documents

TBM Drives at the Gotthard Base Tunnel - Amberg GroupTBM Drives at the Gotthard Base Tunnel 29.8.2017 AFER Certification – Meeting with Amberg Engineering AG Project Main Information